1. Field of the Invention
The present invention relates to a structure for mounting a tube to a header member of the heat exchanger which is manufactured through the use of an expansion wedge. The expansion wedge expands the diameter of an opening of a flat tube to be inserted into a tube hole formed in a header member and which brings the opening into close contact with the tube hole.
The present application is based on Japanese Patent Applications No. Hei. 11-44875 and 2000-23925, which are incorporated herein by reference.
2. Description of the Related Art
According to a known method of manufacturing a heat exchanger, such as a radiator, an opening of a flat tube is expanded while the tube remains inserted into a tube hole formed in a header member, thereby bringing the opening into close contact with the tube hole. Methods described in: for example, Japanese Patent Publication Nos. Sho. 59-180295 and Sho. 60-49861, have already been known as manufacturing methods of this type.
FIG. 14 shows a manufacturing method described in Japanese Patent Publication No. Sho. 60-49861. According to this method, a core section 4 is interposed between header members 1 spaced apart from each other by a given distance so as to be mutually oppose. The core section 4 is assembled by alternating arrangement of tubes 2 and corrugated fins 3.
Respective ends of the tubes 2 are inserted into corresponding tube holes 1a formed in the header member 1. Expansion wedges 6 formed on each of jigs 5 disposed on opposite sides of the core section 4 are inserted into openings 2a of the tubes 2, thereby bringing the openings 2a into close contact with the tube holes 1a. 
Under such a manufacturing method, the openings 2a of the tubes 2 are brought into close contact with the tubes holes 1a, thereby preventing falling of the header members 1 and abating a solder running failure, which would otherwise frequently arise during a brazing process in a subsequent step.
Under such a known manufacturing method, a portion of the edge of the opening 2a of the tube 2 expanded by the expansion protrusion 6 becomes collapsed, as shown in FIG. 15, thus frequently inducing formation of a collapsed portion 2b. 
In the event that the tube 2 becomes partially collapsed, coolant circulating through the tube 2 leaks out from the collapsed portion. For this reason, inspection for collapsed portions requires scrupulous attention and a large number of steps.
Considerable research conducted by the present inventor for solving the drawback of the known manufacturing methods shows that, as shown in FIG. 16, a longitudinal side surface 2c of the tube 2 becomes inwardly deformed during transportation of the tube 2, introduction of the tubes 2 into an assembly facility, or assembly of the core section 4 and that, if an expansion wedge 6 is inserted into the opening 2a in this state, the expansion wedge 6 collides deformingly with the longitudinal side surface 2c, thus inducing formation of the collapsed portion 2b. 
It is also found that, even when the longitudinal side surface 2c becomes deformed, as shown in FIG. 16, spaces 2d remain present in opposite ends of the flat tube 2.